[MPLUGIN-421] descriptor goal fails when there is .java file present with content that's just a comment

[jira-importer]

Leszek Jadacki opened MPLUGIN-421 and commented

Hello,

As I was learning to create own custom plugin, during development process I decided not to compile one of my Mojo's. For ease I simply commented all its content. 

When trying to build my "custom" plugin Install fails when it executes descriptor goal.

It seems like when there is a file in the source folder with .java extension but contains only commented lines the compiler omits the file, but the descriptor is taking it into account and fails during parsing the file with error "syntax error @[X,Y]" pointing to it's last line and column.

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Affects: 3.6.4

[jira-importer]

Slawomir Jaranowski commented

Can you provide a java file which cause a problem?

[jira-importer]

Leszek Jadacki commented

here you go with full project of plugin:

https://github.com/Lesjad/descriptor-fail-poc

 

A story behind:

At first I was playing with concept of Mojo without changing the maven-plugin-plugin version. My problems started when I wanted to use Stream.forEach( {}some lambda expression{}) <- as it is in the code on github. 

build of my plugin failed (on maven-plugin-plugin v. 3.2 also on descriptor goal) without any meaningful message (just a number as an error output). To see it you may simply comment/delete maven-plugin-plugin version change in the provided pom.xml and try to mvn install the project

During my investigation I left some .java file that I wanted to use later but didn't want to compile it until I fix unknown (at that time) issue which outputs just a number.. After finding out that the Stream causes the problem I thought about upgrading the maven-plugin-plugin version to the latest. Then my build failed due to .java file without meaningfull code.

v 3.6.4
reads the sources If im not mistaken in following flow:

org.apache.maven.tools.plugin.extractor.javadoc.JavaJavadocMojoDescriptorExtractor (haven't check other DescriptorExtractors)
uses

com.thoughtworks.qdox.JavaProjectBuilder
which is fed with all files with name ending up with .java in project source paths

then it goes to:
com.thoughtworks.qdox.library.SourceLibrary

where
com.thoughtworks.qdox.parser.impl.Parser

fails when comes to end of file without meaningfull content 

[jira-importer]

Slawomir Jaranowski commented

Wen we execute project with mvn -e ... we will see:

Caused by: com.thoughtworks.qdox.parser.ParseException: syntax error @[8,55] in file:..../descriptor-fail-poc/src/main/java/pan/leszeczek/DummyEmptySourceWithJavaExtension.java
    at com.thoughtworks.qdox.parser.impl.Parser.yyerror (Parser.java:1963)
    at com.thoughtworks.qdox.parser.impl.Parser.yyparse (Parser.java:2085)
    at com.thoughtworks.qdox.parser.impl.Parser.parse (Parser.java:1944)
    at com.thoughtworks.qdox.library.SourceLibrary.parse (SourceLibrary.java:232)
    at com.thoughtworks.qdox.library.SourceLibrary.parse (SourceLibrary.java:209)
    at com.thoughtworks.qdox.library.SourceLibrary.addSource (SourceLibrary.java:159)
    at com.thoughtworks.qdox.library.SortedClassLibraryBuilder.addSource (SortedClassLibraryBuilder.java:174)
    at com.thoughtworks.qdox.JavaProjectBuilder.addSource (JavaProjectBuilder.java:151)
    at com.thoughtworks.qdox.JavaProjectBuilder$2.visitFile (JavaProjectBuilder.java:224)
    at com.thoughtworks.qdox.directorywalker.DirectoryScanner.walk (DirectoryScanner.java:103)
    at com.thoughtworks.qdox.directorywalker.DirectoryScanner.walk (DirectoryScanner.java:91)
    at com.thoughtworks.qdox.directorywalker.DirectoryScanner.walk (DirectoryScanner.java:91)
    at com.thoughtworks.qdox.directorywalker.DirectoryScanner.walk (DirectoryScanner.java:91)
    at com.thoughtworks.qdox.directorywalker.DirectoryScanner.scan (DirectoryScanner.java:81)
    at com.thoughtworks.qdox.JavaProjectBuilder.addSourceTree (JavaProjectBuilder.java:218)
    at com.thoughtworks.qdox.JavaProjectBuilder.addSourceTree (JavaProjectBuilder.java:205)
    at org.apache.maven.tools.plugin.extractor.javadoc.JavaJavadocMojoDescriptorExtractor.discoverClasses (JavaJavadocMojoDescriptorExtractor.java:625)

Which confirms your observations, so the issue is in qdox library: https://github.com/paul-hammant/qdox

Thanks for report issue here - but we can't resolve issue in external library here.

As workaround please not comments everything in source java file.
Or simply remove file, or change extension from java to something else.

[jira-importer]

Leszek Jadacki commented

Thanks a lot for prompt answer and redirection to the library repo :)

also a hint with -e flag is usefull for the future, I was blindly using -X and counted it will show all usefull info :)

regarding suggested workaround - ofc leaving such .java file in the sources would be bad practice and pointless, I just created an issue to support robustness of your plugin as we all try to create "idiot proof" tools and applilcations :)

[jira-importer]

Michael Osipov commented

Still fails with 3.10.2.